Method of making coils for electrical apparatus.



No. 834,220. PATENTBD 0 0'1123, 1906.

- n L. AIKBN'. v MBTHGD 0F MAKING GoILs POR'ELBGTRICALAPPARATUS.

AIWLIUATION FILED AUG. 13, 1902.

' `2 SHEETS-SHEET 1.

IN/EN-ron Edward. Limmen.

No. 834,220. PATENTED OCT. 23, 1906.

` E. L. AIKEN.

METHOD OF MAKING COILS FOB. ELECTRICAL APPARATUS.

' APPLIGA'TION FILED AUG. 1s, 1902.

` 2 SHEETSSHEET 2.

d Edv/ard @maken A tance just sufficient to maintain them ou't of Schenectady,

NITED sTATEs PATENT OFFICE EDWARD L. AIKEN, or sCHENEcTADY, .NEW

YOEK, AssIcNoR To GEN- EEAL ELECTRIC COMPANY, A CORPORATION or NEW YORK. METHOD oF MAKING oolLs FORYELECTRICAL APPARATUS.-

Original applicaticn filed December January 31, 1901, Serial To @ZZ whom it may' concern: I

vBeitknown that I, EDWARD L. AIKEN, a

citizen, of the United States, residing at in the county of Schenectady, State of N ew, York, have invented certain new and useful Improvements in Methods of, Making Coils for Electrical Apparatus, (being a divlsion of my prior application, Serial No.. 45,477, filed January 31, 1901,) of which the 'following is a specification.

In certain forms of electromagneticall -actuated apparatus in which currents 'of arge volume are utilized it is common to form the actuating-coils of but a small number of turns, but with the individual turns of large cross-sectional area in order to carry the currents employed without being unduly heated thereby. Heretofore these-coils have been fashioned out of solid metal by operating upon a blank in the shape of a hollow cylinder. This blank was cut into the required form by the use of a traversing cutter in a screw-cutting lathe, or, if preferred, -by the emlployment of a saw or milling-cutter in a mi ling-machine. The finished article'y resultin from this operation was open to several o jections. Not only was l the article thus formed expensive, but it ossessed in addition the drawback Idue to t e fact that the turns of the helix oi` coil were separated from each other by a considerable space, as was inevitable from the mode of manufacture em loyed. In order pro erly to carry 'out its notion, the turns of t e helix or coil need to be separated from each other only by a discontact with each other. Where' this distance is greater, as was the case in the coil resulting from the mode vof manufacture above Y described, the length of the coil required to obtain a given magnetizing eiiect was' increased, thus requiring the size of the arts operating in immediate 'conjunction t erewith to be increased correspondingly, and so producing a bulky and cumbersome article. A further disadvantage of the old method Awas the resultant waste metal, which could 'only be scra ped.

It is the o ject of the present invention to obvia'te the disadvantages above set forth by producing a coil m which the turns are of comparatively large cross-sectional area and Specification of Letters Patent.

5,1898,Serial No. 698,244, patented February 10, No. 45,47 7. A Again divided and this application led Patented Oct. 23, 1906.

i903, No. 720,092. Divided and application filed August 13, 1902. Serial No. 119,522"` are separated fromeach other by a space of a Width just suiiicient to allow the turns of the coil by their-inherent rigidity to be maintained out of" contact with each other. Instead of cutting the coil out of solid metal I produce a coil freel from the disadvantages of the method of manufacture described by winding a rod, strip, or bar of suitable crosssectional area about a mandrel while at a temperature below that of the softening-jr point of the metal. p In carrying out this operation I make use of ably-shaped working surfaces and movable longitudinally along the mandrel as the rod, bar, or strip iswound thereon, motion being communicated to the guide by reason of the pressure against its working surfaces of the coil as it is -being Wound.' The pitch of the coil is thus determined by the particular character and curvature of the guiding-surfaces and is not due to any external means for feeding the carriage carrying the guide.v

Broadly considered, my invention embraces the idea of winding a bar, rod,` or strip of metal-such, for instance, as cop er or an alloy of co per-on a mandrel of suitable diameter W -le at a temperature below the softening-point of the metal and' preferably 'cold. In the particular method to be described the metal is forced into the required shape by passing .it along the surface of a 'suitable guide or d1e.

Other as ects of my invention, including those more will be more apparent from an inspection of the following description, taken in connecthe scope of the invention oth in its broad and its limited aspects, will be clearly and particularly pointed out .in the appended tion with the accompanymgdrawings, while claims.

In the drawings, Figure 1 is a plan view, and Fig. 2 is a side elevation, of an apparatus employed in carrying out my invention. Fig. 3 is an end view of a twisting-head forming Ypart of the apparatus; and Fig. 4 is a side elevation of the guide, also forming partof the apparatus. Fig. 5 represents an adjunctive device used for separating the turns of a coil when-the coil is closely Wound. Fig. 6 is a 'full-sized cross-sectional outline of the rod employed in forming coils having turns of ted than that above set forth,

a guide having suit- IOO large cross-sectional. area. 7 is a cross-` sectional outline of the rod afterv it is bent and also shows its spaced relation tothe adjacent convolution, and Fig. 8 isa view of a 5 coil as completely finished and ready to be assembled in some electrical apparatus.

The winding apparatus shown in the drawings comprises three essential feat'uresdfirst, the mandrel on which the coil is wound; second, the twisting-head or other device for winding the rod on the mandrel, and, third, the guide through which the rod passes as it is being wound and by which the pitch of the coil is determined. Such in its general na-l 5 turle is the apparatus used for winding the co1 s. had to the various figures of the drawings.

The mandrel about which the coil is wound is a plain cylindrical metallic rod of any desired diameter and is designated in the drawings as 1. In general the diameter of this rod is comparatively small, and it has been found by experience that if the force necessary to wind the coil on the mandrel'were transmit- 5 ted directly through the mandrel itself the mandrel would be twisted and broken off. For this reason one end of the mandrel is mounted so as to be freely rotatable within a cylindrical opening in the twisting-.head 2, the .diameter and the depth of the opening being indicated in Fig. 1 by the dotted lines, which represent the mandrel projecting into \the body of the twisting-head. The mandrel 1 and the twisting-head 2 are mounted 5 so as to rotate, and this rotation is secured by applying force to either or both ends of the barB, which projects through and is secured to the twisting-head. This twisting moment may -be obtained in any desiredl o manner other than in the way described.

Although-,if desired ,a special machine maybe constructed for this purpose, I find it convenient instead of so doin'g to mount the mandrel 1 and the twisting-head 2 between powerful engine-lathe. A center is drilled in the twisting-head in a line with the axis of the mandrel and another center is drilled in the free end of the mandrel. (Not shown.) The twisting-head is mounted on the head-center of the engine-lathe, andthe bar or dogl 3 engages a.suitable projection or profections secured to the face-plate of the lathe.

T he twisting-head already referred gto and shown in detail in Fig. 3 has that end which surrounds theend of the mandrel cut away so as to form a helicoidal surface of less than one complete turn, thevpitch of the helice-id being the same as that desired in the finished coil. lIn order to secure to the twistinghead the end of the ro'd which is to be wound i upon the mandrel, a 'recess is formed in the twisting-head arallel to the axis of the hole or opening dril ed therein and of a depth such 6 5 that thebottom is practically tangent to such As to its details reference must bev the head and tail centers of a sufficiently' sectional shape correspond to the shape of y the rod before being wound, and the recess itself extends along the twisting-head parallel with theaxis a sufficient distance so that the twisting-head kmay obtain a firm grip on the end of the rod which is inserted in this recess. in place after it has been inserted in this recess, a ,sleeve 5 is slipped over thetwistinghead, and a set-screw 6 carried thereby serves to clamp the end of the rod in place. At the point where one side of/"the recess in the twisting-head cuts thehelicoidal surface of the same the metal is cut away so as to form al rounded corner 7. The edge of thisi recess (shown at 8 in Fig. 8) is gradually merged into the helicoidal surface already to and is best shown at 9. The object of this formation is to prevent the presentation of In order to hold the end of the rod referred sharp corners to the rod after it has been inserted under and clamped down by the Asetscrew 6 and with its free end bent around into the position for winding on the mandrel. From the oint 7 the generatrix of the helicoidal su ace of the twistin -head revolves about the axis of the man rel and moves along the axis uniformly from left to right,

k,as will be readily understood. Where this helicoidal surface intersects the wall 10 of the recess el., an angular projection is formed, as shown, perhaps best at 12 in Fig. 1.

In winding a rod, bar, or strip on the mandrel the pitch at which the same is wound is determined, not by feedingvthe rod to the mandrel through the instrumentality of a positively -ltraversed guide', but by feedin it through a guide having surfaces such t at the pressure of the rod against the guidin surfaces as it is being Wound forces the gui e to traverse the mandrel longitudinally, the guiding-surfacesbeing such'that the-` rod is wound on the mandrel at a pitch predetermined by the formation and ,relation of the guiding-surfaces referred to'. In order to permit of this mode of operation, the guide is mounted in such a manner as to be free to move parallel with the axis of the mandrel, but restrained from rotation about it.` Wherethe operation of Winding is carried on in an engine-lathe, the guide may be mounted on the slide-rest of the lathe, the longitudinal and cross feeds of the slide-rest being disconnected, so as to allow thesamefree motion alongtheggays of the latlzi.v resisted only by the fictioiiincident to such motion.

In matter of detail, the `guide may either be cut out of solid metal or built up from separate piecesfor convenience in mechanical construction and operation. ficulty, however, of forming the required guiding-surfaces out of a solid block of metal,

I find it more convenient to fashion the same out of separate pieces, thepieces being bolted IZO Owing to the difl,

. line ,formed by the intersection of these two together in proper relation when finished.

In the .drawings I have shown the guide as made in two parts ,which I find it convenient to designate as 'af base and a cap piece. The base is indicated at 13 and has formed thereon straight guiding-surfaces, along which the rod or the like'is passed as it is fed to the emandrel. These straight guiding surfaces consist of two intersecting planes, one of which is parallel to the axis of the mandrel and is approximately tangent to the coil after it-iswound on the mandrel, suflicient space, however, being left between this surface and the surfaceof the coil to allow for clearance. The other surface of the straight guide is formed by a plane which intersects the plane guiding-'surface already mentioned, and isV inclined thereto at an angle less than a right angle. This angle is such as to coincide with the angle made by the base of one side of the rod or bar asit passes to the mandrel. The

guiding-surfaces is inclined to the axis of the mandrel at an'. angle corresponding to the pitch of the coil to be wound, as will readily be understood. The two guiding-surfaces spoken of are perhaps best indicated at 14 and 15 in Figs. 2 and 4, and the rod to be bent is shown in cross-section adjoining these surfaces in Fig. 2. of the guide is -planed away parallel to the surface 14, so as to be on a level with the top of the rod when placed in position against the guiding-surfaces, the construction being best shown in Fig.- 2. The cap-piece 1 6,

. which forms the other partv of the guide, consists of a block of metal having a hole drilled therethrough of such diameter as to make a working fit with the mandrel. For a portion of its length parallel to the axis of this hole the cap-piece is planed away tangent to the hole, thus leaving the cap-piece with a downwardly-projecting lip, which'makes a right angle with the flat cut-away portion. The plane along whichthe cap-piece is cut away is clearly-shown at 17 in Fig. 4. `The'cap piece is fitted over one edge of the base 13 y and is secured thereto by bolts 18, which pass through the downwardlyrejecting lip of the cap-piece intov one side o the base, and by bolts `19, which pass down through the cap-piece into the base-piece. That sideof the cap-piece whichis nearest to the plane guiding-surfaces 14 and 15 ,(lready described, is cut into a guiding-surface inthe form of a helicoid, the generatrix-of which makes a right angle with the axis of thev hole in the' cap-piece and the pitch of which corresponds to the pitch of. the coil to be wound.l Owing to the fact that the guiding-surface 15 (shown in Fig. 4) is inclined to the axis of the opening in the cap-piece at an angle different from the inclination to such axis of the gen- -eratrix of the helicoidal surface formed on such cap-piece it is evident that the two sur- The top surface of the basev -in Fig. 2.

faces can never be so related asl to pass,v

smoothly from one into the other. The angle which would otherwise be formed when this f condition is obtained, as nearly as possible,

is therefore cut and smoothed away, so as to,

merge one surface into the other. The point at which this merger takes place is indicated approximately at 33, Fig. 4. The helicoidal surface proper of the cap-piece commences along the line indicated at 20 and terminates along'the line 21, which 'indicates the outer edge of the projecting angle of the cap-piece, under which passes the rod to berwound, as will be seen from Figs.Y 1 and 4.

It is yof course to be understood that the 8c guide as a whole is bolted or otherwise secured to the slide-rest of the lathe, so thatthe hole in the cap-piece has its axis in Icommon with the axis of the mandrel, and so that the mandrel as a whole is free to rotate and slide inv the opening in the ca -piece.

The rod or bar w -ch is to be wound is maintained in contact with the straight guiding-surfaces by means of a roller 22, carried by an adjustable plate 23, held down by bolts 24 to the top surface ko f ythebase 13. The` guide or antifrictional roller 22 is in the forni of a truncated cone, of such nature as to bear downwardA projection of the plate 23 and bearing agalnst the side of the base 13.

l In winding a rod of any appreciable thickness about a mandrel the outer circumference of the finished coil is greater than the inner circumference, and it consequently follows that the metal on the -outer circumference of the coil is stretched, while that on the inner is condensed or compressed. As aresult of this action the crosssection of a turn of the finished coil is'di'erent from the crosssection of the rod or bar before being wound, the Width of the outer dimension of a turn of .the coil being less than the'corresponding dimension of the bar from which the turn is formed. In order, therefore, to obtain a coil in which the. turns have a cross-section substantially rectangular, it is necessary to employ in making the 'coil a rod orA bar the crosssection of which is trapezoidal, the rod'or ba'r being fed to the mandrel with its shorter parallel side in yContact. therewith. If the-` trapezoidal section of therod or b ar properly corresponds to the diameterof the mandrel yand the pitch of the finished coil, the trapezoidal section will be changed to a rectangular section duringthe process of winding. A

ICO

bar of the trapezoidal section referred to is shown in Figs. land 2 in the operation of being wound on a mandrel. i

Where rods or bars of large cross-sectional area are wound, it has been found in practice that the edge. of the coil in contact with the mandrel lbulges out under the' longitudinal and radial compression, so as to cause the turns in a closely-wound coil to make contact with each other along their inner edges. In order to allow for and prevent the .metal from iiowing in this manner, I chamfer or cut 'away the corners formed by the intersection tion of the mechanism described. The end `of the bar to be wound is bent nearly to a rightangle and is inserted in the twistinghead 2.,in which it is secured by the set-screw 6, carried by the sleeve 5. The guide 13 is brought up and the straight guiding-surfaces thereof placed in contact with the rodor bar as it projects from the twisting-head. The antifriction-roller 22 and its carrying-plate 23 are then secured in position and the operation of winding upon the mandrel 1 is thenv ready to commence. As the twisting-head is turned the rod or -bar is gradually drawn into the guide and is forced to traverse the straight and the helicoidal surfaces thereof and lin so doing is bent into a helicoid the pitchof which corresponds to the pitch of the elicoidal surface of the'giii'de. By properly proportioning the width of the bar or rodto e wound to the pitch of the helicoidal surface of the guide acoil may be obtained with any desired distance between the turns. For the purpose for which I inted to employ then coils made by this apparatus this proportion may be made'such as to leave just sufficient -distance between the1 turns of the coil to maintain them out of contact, although 'it is' obvious that -any other desired proportions may be employed without departing from my invention. y n In some cases where the turns of the coil .are not olii *unduly large cross-section the turns are wound' closely together and are afterward separated by screwing through the coil and'between its turns asmall section of 'iin-like screw-thread. Such a screwthread, together with its carrying-mandrel, is shown in Fig. 5, in which 26 indicates the mandrel proper, 27 the sleeve forced byA rIrieans of the nut 29 against the short sleeve carrying the screw-thread 28. The pin 30,

engaging with the mandrel and with the sleeve bearing the integrally-formed screwthread 28, prevents the screw-thread from turning about the mandrel 26. Y

In Fig. 8 is shown a view of the coil in its finished condition and ready to be assembled in an electrical apparatus. This coil consists of a small number of turns cut from the long length of coil ordinarily wound in one operation of the mechanism above described. To the ends of this short length of coil anglepieces 31 are secured by sweating and brazing or in any other manner to give good electrical connection. Bolts 32 are secured to the projecting ends of the angle-pieces and serve both as mechanical supports for the coil and as conductors for conveying the current supplied thereto.

Although the coil of the nature described and the method and apparatus for manufacturing the same as above set forth are peculiarly applicable in connection with the manui facture of electrical apparatus, it will of course be evident that my invention as re# gards' these features is not to be limited in its scope to any particular ,utilization of the product which is the result of my invention.

What I claim as new, and desire to secure by Letters Patent of the United States, is-

1. The method of forming helical coils with uniform spacesbetween the adjacent edges of the respective turns, which consists in forcing a strip of metal of large trapezoidal cross-section into the shape of a helix with its respective turns in contact and thereafter separating said turns by causing a spreader to pass therebetween to produce a permavnent set in said turns.

2. The method of forming an electromagnet-coil consisting in giving a" bar of metal a substantially 'trapezoidal section and with the inner corners chamfered, and Winding said bar about a mandrel whereby the innermost parts Vare compressed longitudinally and radially, and the outermost parts are eX- tend'ed longitudinally and contracted trans'- versely so that the respectiveturns of the coil may be separated by spaces ofuniform width. j j

In witness whereof I have hereunto set my hand this 8th day of August, 1902.

EDWARD L. AIKEN.'

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